text:
What is the advantage of increasing an aircraft's horizontal tail surface area?
Most aircraft have horizontal tails. What is the advantage of increasing the horizontal tail surface area?

Better pitch stability,

More explain please @ratchetfreak

Increasing horizontal stabilizer area increases pitch stability and the permissible range for centre of gravity at the cost of some aerodynamic efficiency.
Stability in pitch means that the aircraft tends to maintain constant angle of attack (which roughly corresponds to maintaining constant speed with pitch). An aircraft is stable in pitch if the aft surface flies at lower angle of attack than the front surface (this applies to both conventional tails and canards).
Making the horizontal stabilizer larger does the following:

The absolute change in lift force on the horizontal stabilizer when angle of attack changes is larger, so the aircraft returns to the trimmed angle of attack faster (increased stability).
As centre of gravity moves aft, the difference in angle of attack between the surfaces decreases to keep the plane balanced, reducing pitch stability. If the horizontal stabilizer is larger, the angle of attack changes more slowly for the same change in lift, so the centre of gravity may be permitted further aft before the aircraft becomes not stable enough.
As centre of gravity moves forward, the difference of angle of attack between the surfaces increases until angle of attack of the horizontal stabilizer exceeds its stall angle of attack and control is lost. If the horizontal stabilizer is larger, it can provide more (downward!) lift before it stalls, so the centre of gravity can be permitted further forward before loosing control authority.

Maybe it is worth mentioning control forces. They should increase with the square root of the increase - less deflection needed, but a bigger area to move.

Whereas the question does not ask for drawbacks, you may consider including them in your answer for completeness.

Previous answers highlight two separate issues: effects on stability and effects on control power. Its difficult to predict control power changes in the context of your question - is it an all moving stabiliser or is it an elevator (how is the configuration of the elevator changed?). If we look at the effect of increasing horizontal area when a perturbation occurs without motivator (control surface) movement, thus isolating control power changes if any, and assuming moment of inertia isn't changed in the pitch axis (which it probably will with a larger tail), then the dynamic and static stability of the aircraft will change.
Assuming a statically stable aircraft: Dynamically, the natural frequency of the aircraft should increase. Statically, assuming the motivator generates the same lift force for a given deflection, then more control surface movement will be required to achieve the same alpha. Ultimately, the control power left will be reduced as more power is needed to counter increased stability. Hence as mentioned, the aircraft CoG working range will be reduced.
WRT control forces and what is 'apparent' to the pilot, this will depend on the flight control system employed. For reversible controls, conventionally stronger stick forces and larger displacement may occur (not guaranteed), however non-reversible systems with complex computer arrangements may manifest as something completely different. A moot point given we're in a completely hypothetical question.
So we talk about the 'effects' of changing area as opposed to 'advantages and disadvantages'; the aircraft design is tailored to achieve the intended application.


text:
Are modern Airbus aircraft protected from excessive rudder input?
When in normal Law are Airbus aircraft now protected from the types of excessive rudder input that caused the crash of American Airlines 587 (as dramatized in Mayday, S13E05)?

There seems to be a misunderstanding here; the A300-600 uses a mechanical hydraulic link between the foot pedals and the rudder, and so flight envelope protection could not hope to do anything.

@raptortech97: Note the word "now".  I think this is asking about the A320 and newer Airbus models which do have flight envelope protection, unlike the A300.

@NateEldredge could be

Yes, A320 and all newer models have rudder travel limiter that limits the maximum rudder deflection depending on speed.
It should be noted, that this has nothing to do with normal law. Normal law governs pitch and roll. Rudder is controlled by (hydro)mechanically connected¹ pedals and yaw damper, which is independent from the system controlling pitch and roll and simply reacts to side-slip (lateral acceleration actually, only A350 will have side-slip vanes) induced by the roll.

¹ Different Airbus models have different subset of controls with direct hydromechanical link as a backup in case of electric failure, so I am not sure rudder pedals have it on all models. They do on A320.

I am not sure that rudder travel limiting based on speed would be able to prevent the type of structural failure that caused the crash of AA587. The vertical tailplane sheared of because of extreme sideslip angles caused by multiple cycles of alternating rudder input.

@DeltaLima: I understood it so that the limit should be such as to not allow so large excitation. But now that you say it, I am not completely sure either.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


text:
How are landing minimums decided?
How are landing minimums decided for a flight? Does the captain make the decision depending on weather conditions or is it preset for each airport?

The terms you are looking for are Decision Altitude (DA) and Decision Height (DH). If no visual reference to the runway is established at the DA or DH, a missed approach has to be initiated. So based on the weather and the certification of the airport (CAT I / CAT II / CAT III), the pilot will make the decision to land or not land at the DA/DH.

(Image Source: SKYbrary)

Decision altitude (DA) is referenced to mean sea level and decision height (DH) is referenced to the threshold elevation.
The DH for Category II and III approaches is invariably assessed by reference to a radio altimeter and never a barometric altimeter; therefore the minima can only be expressed as DH and not DA. For approaches with DH of 200ft or higher, radio altimeter reading would be unreliable due to the unevenness of the terrain; therfore a barometric altimeter is always used and the minima may be expressed as DH or DA.
The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path. In Category III operations, the required visual reference is that specified for the particular procedure and operation.
For convenience where both expressions are used they may be written in the form "decision altitude/height" and abbreviated "DA/H"

Related Videos:
CAT II ILS Approach LGTS
Related Questions:
Is it legal to land in bad visibility conditions without ILS?
Are zero visibility landings practical and desirable for commercial aviation?
How can landing in zero visibility be safe?

It is different and set at every airport, at each runway, for each category (size) of plane, and for each procedure that is followed.  For example a VOR approach has higher minimums than a Localizer and then again than an ILS because of the precision of the approach.
In general almost every approach to any IFR runway has different minimums including if it's a straight in (lower) or a circle to land (higher).
There are also planes with radar ground sensing that can fly what are called CAT III approaches and can land in almost zero-zero weather.  Those are highly automated and computer controlled landing systems.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Could someone use an axe to break through a locked cockpit door?
Could someone accomplish entry with an axe, considering how tough cockpit doors are?
Do planes carry axes?

I heard they are bulletproof steel reinforced, so I would guess no (but I'm far from being an expert in anything but being a passenger). Follow up question though, instead of focusing on the door, can't you just hack through the dividing hull? It's a life or death situation, if you accidentally cut up some electronics, who cares? As long as you get a chance to survive, I mean.

Towards what end? Why restrict this to a pilot doing this? Why not ask "could an axe be used to bypass a locked cabin door".

Mainly because my unedited question was referring to the 4U crash, but yes that would make sense

The best solution is to go around the door. Forget breaking it.

The best solution is to remove the passengers. Then the door is not needed any more - less weight on board. More seriously, though, I am starting to think reinforced doors were a temporary measure that have never really addressed the underlying security problem.

Axes are not carried in the cabin and the door is designed to resist attack using tools available in the cabin

Fire/crash axe/crowbar. Fire axes were provided to obtain emergency access to areas and parts of the airplane which are not easily accessible (e.g. behind sidewall, electrical or ceiling panels). The handle is insulated to protect against electric shock. In the past, fire axes might be found in the flight deck and in the passenger cabin but on most carriers, in compliance with anti-terrorism regulations and procedures, axes are no longer carried and have been replaced by insulated crowbars in the passenger/cargo compartment.

From http://www.skybrary.aero/index.php/Cabin_Fire


text:
Are pilots expected to keep an ear out for conflicting authorizations?
I just watched the Mayday episode Cleared for Disaster, a dramatization of USAir Flight 1493. The episode covered how the controller lost situational awareness and gave a landing clearance to 1493 while SkyWest 5569 was still on the runway, as well as how the runway lights obscured 5569's lights. They did not, however, talk much about 5569. This was at least partly because 5569 was not carrying a CVR.
The tower would have given 1493 the clearance to land on runway 24L on the same frequency that 5569 should have been on. In other words, 5569 would have been sitting on 24L and hearing tower give landing clearance for 24L, which would be a big red flag. Are they expected to be listening and thinking about landing clearances given to other aircraft? If they noticed, would they be expected to speak up, or to shut up and trust the controller?

The short answer is yes, they are definitely expected to listen and act accordingly. This is one example of situational awareness in aviation, and pilots are expected to use all useful information sources to maintain awareness of what's going on around them.
A nice example is this one where the crew of a US Airways aircraft avoided an accident. There was heavy fog at the airport, and while the US Airways flight was waiting for takeoff clearance a United aircraft ended up on a runway instead of a taxiway. The controller couldn't see the runways because of the fog and she believed the United aircraft was on a taxiway, so she gave the US Airways flight clearance to take off even though the United pilot said several times that they were on a runway.
The US Airways pilot had heard the discussion (actually, almost a debate) between the controller and the United pilot, and he refused the takeoff clearance because he wasn't confident that the situation was under control. It's well worth watching the whole thing, but the key exchange is this:

ATC: [...] USAir 2998, runway 5R, fly runway heading, cleared for
  takeoff
US2998: Uh, tower, USAir 2998, 'til we figure out what's going on down
  there, we're just gonna stay clear of all runways

This level of awareness is expected of all pilots, including light aircraft pilots at uncontrolled fields. Although in that situation there's the additional complication that there may be aircraft around that don't even have radios!

Short answer, never trust the controller.  If the worst happens all the controller will have is paperwork to do and lots of meetings.  But your family will have your funeral to tend to.  As PIC you are the sole authority as to the safety of your flight.  As for listening, IMHO, it's more important to listen carefully at takeoff and landings.
We train ourselves, while in the air to listen for the 1st word which is the call-sign of the aircraft and if it's ours then it has our attention and if there are other passengers on my plane my hand goes up for them to keep quiet.
But during landing, approaches, etc, we must familiarize ourselves not with just the approach or runway we are landing on but we should know the configuration of the airport in general.  In single runway airports, it's not as hard.  You just have to know which runway is landing and taking off and if you hear other wise then you speak up.    In multiple runway airports, especially with low visibility if you are still high enough, do not be afraid to key up and ask a question.  Just as you would key up even without a call-sign and ask 'Wind Check'.   The controllers then broadcast the current winds in the blind.
But if you are on short final and are still unsure, there is only one thing that is the safest. Abort the landing, and do a go-around as you are informing the tower you are going around because of unclear instructions.
If they give you a number to call because you messed up their nice string of pearls they were setting up, giving them more workload, or messed with their approaches and departures, that's fine.  Like I said above, I'd rather be on the ground talking to, explaining to or writing up documents (especially a NASA form) than having someone crawling over the mangled mess of my airplane trying to figure out which part was part of me or someone else.

" If the worst happens all the controller will have is paperwork to do and lots of meetings." That seems harsh and inaccurate. In this case, the crash had a major psychological effect on the controller and she never returned to air traffic control. Also, note that 5569 is the plane on the ground, not the one in the air.

Sorry for understating the grief all around.  It was not my intention.

Unless the plane crashes into the control tower or facility.

This post seems very arrogant and dismissive to me.  If the worst happens all the controller will have is paperwork to do and lots of meetings. - really?  If they give you a number to call because you messed up their nice string of pearls they were setting up, giving them more workload, or messed with their approaches and departures, that's fine. - really?


text:
How much lift do planes produce before rotation?
In the takeoff roll, I'm pretty sure planes produce some lift before rotation, but how much? Is it insignificant compared to post-rotation, or is it large compared to the post-rotation lift?

Check out this plot (taken from wikipedia), of the lift coefficient against angle of attack. During takeoff roll, lift will be increasing due to the speed increasing, however not enough (in general) for the plane to achieve takeoff without rotation.
Once rotation starts, the lift increases dramatically, for (a very rough) example, consider a plane on takeoff roll, then rotating to 15 degrees angle of attack. By looking at the lift/AoA plot, we can see that the lift coefficient increases from roughly 0.55 to 1.7, giving roughly 3 times as much lift as before rotation.

Just to add, during take-off high lift devices are deployed, making the curve above (depending on the devices) moved up, making less dramatic (relatively) the lift change. Also to take into account the ground effect.

Very good points

In high crosswinds in a taildragger, we keep the stick forward to keep the wheels in firm contact with the ground. As soon as you release the pressure it'll fly off the runway. Very little back pressure is required.

Rotation increases the angle of attack, and as a result, the lift force also increases. However, there are aircraft that do take off with very little angle of attack change (maybe a couple of degrees, as in the case of UAVs). For those aircraft the lift force before rotation can be 60-70 % of the weight of the aircraft. Remember, for take off to happen, the lift force must be at least equal to the take off weight.
One more parameter is, of course, the airspeed. The lift increases with the square of the airspeed. And at the time of rotation, comparing just before and just after liftoff, the lift generated are quite close to each other, depending on the change of alpha (angle of attack). At a stationary airplane, with no headwind, there is no lift (ignore engine flow).
To sum up, during the ground roll, from standby to rotation, the lift increases from zero to a large fraction of the weight. The fraction depends on the type and design of the aircraft, but cannot be equal to the weight.

Take the B-52: It doesn't rotate but accelerates until it flies. Here, lift is 100% of weight before take-off (on a level runway).

@Peter, I'm not sure the B-52 really allows no-rotation for takeoff; at a small wind gust or disturbance, the plane would lift and touch again, depending on the magnitude. However, touching on and off would probably not cause hazards, so it may be that way.

Having read a bit more about the B-52, and after watching a take-off video, i guess they just let it float into air. But a pilot has said somewhere that he tries to keep the rear wheels on the ground, this sounds like there is some rotation implied?

The forward wheels of the B-52 are so much forward of the center of gravity that there is no chance in hell that the rear wheels will lift off while the front wheels are still on the ground. Pilots sometimes use strange rationalizations for their actions.


text:
Does the FAA verify or authorize VFR flight plans?
It's possible (and, at least by AOPA, encouraged) to submit flight plans for VFR flights, but ATC still do not perform many of the services they provide for IFR.
Suppose I submit a flight plan for a Piper Cub under which I take off, climb to FL10,000, and dock with the International Space Station before landing on the White House front lawn? Or, slightly less egregiously, a plan under which I clip an ADIZ but I don't mark it as DVFR?
Will the flight plan be rejected when I try to submit it? Will Flight Services refuse to open it? Will they open it anyways and just let me do my thing?  Are they required to verify it in some way?

I'm not sure if space shuttles fly VFR...

@kevin good point! Clarified that.

For the first one, I don't imagine they can enter it into their computer, so they'd probably notice and say something.

My comment will be a dumb question: does the FAA verify or authorize an IFR flight plan?

At that altitude you will have to lean your mixture to a point the cub may not allow. Not to mention that an individual in full EVA gear with required O2 would most likely be over the useful load of the cub.

@Dave the suggested flight plan was not intended to be in any way realistic. There are also other issues; the engine would starve and the wings would lose lift without such a thin atmosphere at such altitude, and the Cub's max speed of 141 km/hr falls slightly short of the ISS's orbital speed of 7.6 km/s.

@raptortech97 I know just thought I would throw it out there :). I dont actually know what would happen if you tried to file such a flight plan. But you can always call the FSS and try it. If they approve it just close it right after.

First, one small clarification: ATC doesn't offer any services to an aircraft on a VFR flight plan unless you call and request them.
This short Ask ATC video from AOPA has some useful comments:

Controllers don't know anything about your VFR flight plan
VFR flight plans are for search and rescue purposes only
Even if you call ATC and request flight following, they only enter the destination into their system, not your route (I assume that's because your route could be 'follow that river and then that interstate')

The key point is that VFR flight plans are recorded and managed by FSS, not ATC. So, does FSS accept whatever they're given? I couldn't find a direct answer to that question, but the FAA's procedures for receiving and handling VFR flight plans (see Chapter 6) don't include any steps to "validate" the plan (whatever that would mean anyway). Although there's a lot of detailed, tedious information there so I may have missed something :-)
In fact, this AOPA explanation implies that no one even looks at the route unless it's as part of the SAR process:

ETA plus one hour
Within a half-hour of becoming overdue or at ETA plus one hour, the
  search is widened by sending an INREQ (information request) to flight
  service facilities along the route (which is why the route of flight
  is specified on the flight plan). If [the pilot] had been on an IFR flight
  plan, the INREQ would have gone out at ETA plus 30 minutes.

The bottom line seems to be that no one really cares about your VFR flight plan unless it's actually needed to find you. So even if you can enter a nonsense plan, it wouldn't be a very good idea.

The link to the AOPA explanation above has suffered from link rot. Here's a link to the the article from the Wayback Machine

No verification is done.  You may file what you will.
This places all the responsibility for airspace incursions on the pilot in command ("PIC") where it belongs.
The only real effect of the VFR flight plan is to engage the Search and Rescue folks if you don't close the flight plan on time, and give them the route you intended to fly when you filed so that they know basically where to start the search.  Note, the first thing the SAR folks will do is call your intended destination to see if you have arrived.  If no, then the search begins in earnest.

This is great answer! Any chance you could add references or the source of authority?

Defense VFR Flight Plans used for penetrating an ADIZ are a quasi-exception to the FAA's general "we don't care" attitude about VFR flight plans: The flight plans are still not "verified" & the responsibility for airspace avoidance is on the pilot, but ATC will be expecting certain things of the pilot, including a good estimate of ADIZ penetration time, and prompt communication if that estimate is going to be wrong. (There's probably a nice Advisory Circular about this but the governing regulation is FAR 99)

@raptortech97:  see the AIM (Aeronautical Information Manual) paragraph 5-1-4.

The part I see that seems relevant is "It is strongly recommended that a flight plan (for a VFR flight) be filed with an FAA FSS. This will ensure that you receive VFR Search and Rescue Protection." That implies there are no other significant benefits to the pilot, but not that FSS will accept a patently ridiculous flight plan. In fact, I see "Block 11. Enter only those remarks that may aid in VFR search and rescue, such as ..., or remarks pertinent to the clarification of other flight plan information, such as.... Items of a personal nature are not accepted." (Emphasis mine.)

So the FSS might refuse to enter certain parts of certain plans. That suggests it might be possible for an operator to refuse to enter a ridiculous plan.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Does a Mexican citizen studying in the US with an FAA license need a visa when landing at airports in Canada?
I'm from Mexico but worked in San Francisco for 4 years under a TN Visa. During that time I learned how to fly and obtained a PPL and then an IFR rating.
I'm now living in Boston getting a Masters Degree under an F1 Visa. I'm interested in flying into Canada. Canada requires visas for Mexican citizens, but a friend claims that there's an exception for pilots. I only want to check out Montreal, so I would be in Canada for 48-72 hours max.
What's a good resource to see visa requirements for pilots from different countries flying into countries other than their own?
Thanks!

Meta question: http://meta.aviation.stackexchange.com/questions/1579/is-immigration-customs-advice-specific-to-pilots-on-topic-here

Canada's immigration website is quite clear: if your passport lists your nationality as Mexican, you need a visa to enter Canada.
In general, a visa for one country will not affect whether or not you need a visa to visit another country; in this case, your F1 does not change the fact that you need to get a Canadian visiting visa. I have no idea whether it would affect how easily or quickly you're able to get it, though.
Some countries, such as the US, have a special visa for air crews, and private pilots might qualify in some of those countries.

In some cases, the special visa is more than you need if you aren't a pilot (e.g. Canada-US, where Canadians don't normally need a US visa).

@cpast the State department website has a list of reasons why Canadian citizens might need a visa, and that list doesn't say anything about pilots needing visas...

I stand corrected for Canada. However, VWP countries aren't exempt from this visa; an airline exec from the UK going to a conference in the US needs no visa, but a British pilot flying an airliner there does.

You should call the Embassy of Canada in Mexico for advice on your situation. They will best be able to advise a Mexican passport holder on their entry requirements. Their number is +52 55 5724 7900.

This is almost a link-only answer, but not quite...

Strictly speaking, I would consider this to be travel advice rather than aviation advice.

I don't see where you're going with that...?

@MarkyMark -- pilots get treated somewhat differently under immigration law for fairly obvious reasons, so I wouldn't call it completely off-topic here

I can't speak for that specific case but I do remember a friend of mine flying to Russia from Germany (not Mathias Rust...). For a simple touch and go he wouldn't have needed any visa. But leaving the plane under whatever circumstances is immigration and thus requires all the papers any other immigration would. Furthermore: As a private pilote you do normally not qualify for the pilot visa as they are often restricted to the staff of airlines recognised as such by the respective authorities.


text:
Is head-on or trailing wind better?
Does a powered aircraft fly faster when in a head wind or with a trailing wind? The question revolves around the head wind should provide 'better' lift, and trailing winds have very little to 'push' against.

It might not be obvious from the answers, but "how fast" is not a simple question.  Through the air (airspeed), it will be the same with headwind or tailwind.  Over the ground, it will be airspeed + tailwind or airspeed - headwind.  A bit simplistic but roughly accurate.

@Simon good point. OP should respond and clarify, though I suspect if he understood the difference between groundspeed and airspeed, he would not actually be asking this question in the first place. My guess is he means groundspeed.

A tailwind provides a faster groundspeed.
The aircraft moves through the air so whether the ground is moving relative to the mass of air has no relevance to the aerodynamics of an aircraft at cruising altitude.

a British Airways passenger jet approached supersonic speed this week as it rode a surging jet stream from New York to London.

from The Telegraph, 10 Jan 2015
They mean groundspeed - so the term supersonic is moot.

The Boeing 777-200 jet reached a ground speed of 745mph as it rode winds of more than 200mph across the Atlantic. At ground level, the speed of sound is 761mph.

Aircraft often use the predominantly westerly† jetstream when flying from the USA to Europe, From Japan to California or across the USA. Flying the other way they pick an altitude to avoid it.
 Wikipedia
The Jetstream is a high speed, high altitude, wind that blows moderately reliably in one direction.
 Metcheck
† Westerly means "blowing from the west" - towards the east.

I remember seeing that story about the BA flight and wondering why it was considered newsworthy. Both times that I've flown from Asia to the U.S., we've had ground speeds that would have been well over Mach 1 in still air. It makes a difference when you have a 180 mph tail wind. LAX->HKG was 15 hours, while HKG->LAX was only 12 (77W both ways.)

@PieterGeerkens:  as we operate in a coordinate system tied to the earth, that doesn't matter at all. It is true that relative to an inertially fixed system the earth rotation is faster than any wind.

Headwind is good for take-off and landing. It adds extra speed for free at the start of the take-off run, rsp. allows to come in slower for landing, reducing the landing distance.
Tailwind is good for enroute flight. It pushes the aircraft forward and adds extra miles per hour for free. The speed relative to the surrounding air is the same at the same power setting and altitude regardless of wind speed, but when measured relative to the ground the wind speed must be added to the air speed.
But on the way back from a tailwind leg the aircraft has to fly in a headwind, and the added time and fuel expense is higher for the sum of both trips in comparison to trips made when no wind is blowing. Why? Let's assume the aircraft will fly at the same power setting, and will achieve 200 mph in still air. The trip to a destination 1000 miles away will take 1000 / 200 = 5 hours in still wind for a roundtrip time of 10 hours.
Now add to that a 50 mph tailwind, and the trip will take 1000 / 250 = 4 hours. On the return trip we need to subtract the wind: Now it will  take 1000 / 150 = 6 hours 40 min to fly back. The total flight time with wind is 10 hours 40 min, and those 40 min of longer flight time consume proportionally more fuel and crew time.
Tailwind is only good when you don't plan to return, or when the wind will have changed when you go back.

Or when you can take a different route to avoid the winds, as RedGrittyBrick describes with jet streams

Well, you lose something. On a flight PRG-CDG (westbound) with easterly wind, you get extra speed during the flight for free, but you take off and land the opposite direction, making a half-turn on both ends, which costs some time. If you get a westerly wind, then you don't turn at all during the whole flight, but you get a headwind all the time that slows you down.

@raptortech97 Or when you merely fly at a different altitude with less wind on the way back. This is a pretty common practice in GA, at least. Wind can vary a lot by altitude.

Constant wind does not affect the lift or drag of an aircraft.
As stated by others, you will travel faster in relation to the ground with tailwind but your airspeed will stay the same no matter what wind you have.
Shortly after you are in the air, the aircraft travels with the wind, rather then with the surface of the earth. The aircraft wouldn't notice any wind. For an airborne aircraft, the air always stands still. Wind is only the movement of air in relation to the ground, and the aircraft doesn't relate to the ground once it is airborne.
If you are having tailwind, the aircraft will travel with the same speed through the air, but with an increased speed over the ground. This is why you take off into the wind: Your airspeed (the speed the aircraft travels through the air, so the sum of windspeed and groundspeed) is higher with a lower ground speed.
Here the maths: Let's say you have 10kt headwind and you are standing at the runway. When standing still your airspeed is already 10kt eventhough your groundspeed is 0kt. As you start moving, the airspeed will always be 10kt more then your groundspeed.
Conclusion: The wind doesn't make an airplane faster in relation to the air, but in relation to the ground the wind can change the speed of an aircraft, but not by producing more lift/drag, but by simply moving the aircraft along in the air.

Let us continue this discussion in chat.

The question actually has nothing to do with aerodynamics. It's a matter of relative motion, which is traditionally considered physics, but IMO is really nothing more than simple vector arithmetic.
Consider this equivalent question:
Before you board your airplane, you walk through an airport. You approach two parallel "pedestrian conveyor belts," one moving away from you and one moving toward you. Which one should you walk across if you want to get to the other side faster?
Now replace your body with the airplane, and the conveyor belts with "wind" (moving masses of air). Does that make it more clear?

This is a bad analogy, because while you get easier on the belt that moves in the same direction as you do, the plane gets easier on the belt moving towards it.

I am not sure what you mean by the words "get easier," could you please use more specific words? Disregarding takeoff and landing (which makes sense since OP specifically mentioned a plane flying), the plane will make better groundspeed, i.e. arrive at its destination sooner, with a tailwind, i.e. on the belt moving in the same direction it is moving.

Yes, I do mean take-off and landing.

Yes, take-off and landing are preferable in a headwind only because of runway distance constraints. However, if you are interested in getting from point A to point B as fast as possible and have very long runways, then tailwind is still the way to go. :-) OP seems most concerned with speed, and with vehicles already in flight.

I doubt your statement. Since for instance PRG (the airport I know the best) flies now almost only small aircraft, but has a runway made for 747, why would they ever change direction? ... (this is getting irrelevant, so let's stop it probably)

Probably because planes are not designed for traveling on the ground at high speeds. And most crashes happen on takeoff and landing, and crashing is preferable at low groundspeeds. :-) So to answer your question in one word: safety. But in terms of pure math, my statement is accurate.

Yes, there is a maximum safe speed when on the ground (having to do with tires/brakes/etc.) Also, you want to reach V1 quickly so that if you had to abort, you still have plenty of room to stop without setting the brakes on fire. From a pure efficiency standpoint, though, you're right that just taking off in the direction you want to fly is more efficient.

When looking at the physics, the speed of an aircraft is the speed relative to the air. For this, it is not relevant how the air moves relative to the Earth - or any other planet, for that matter.
The aircraft does not even "know" the direction of wind.
So there can not be a difference in the aerodynamics, in a very fundamental way.
If you ask about the speed relative to the ground, you can just add the vectors of both speeds.


text:
For routes over oceans, are slide rafts fitted with first-aid items, food, water, radio, etc?
Nowadays life rafts are often replaced by slide rafts, the slides having a double function: Evacuation and when detached survival. However they are packed tightly in the aircraft doors, so they probably don't contain a survival kit.

Nice illustration by Ron Wilson
Though it would be typical of ditching on Lake Michigan, not in heavy sea
For routes over oceans, what is the equipment that is available aboard rafts when they are used? (first-aid items, food, water, radio, etc). Where is this equipment stored before evacuation? Who takes care of making this equipment available in each raft?

I would be surprised if food and water are supplied.  Its not expected that these become long-term life-rafts.  Rescue should typically be less than a day away.  The urgent need would be medical supplies, not food/water.


text:
How is the quadrantal rule applied to VFR flights in Hungary?
I'm looking for a clear explanation for this quadrantal rule question (it applies to Hungary):

A VFR pilot is cruising, en-route in level flight, above the transition level of FL035. His magnetic heading is 355°, and he sees that by having allowed for 8° of starboard drift he is exactly on track. What would be an appropriate Flight Level for the pilot to choose in accordance with the Quadrantal Rule?

What country does this apply to?

Hungary. This question is from a PPL theory questions book.

I've added that information to your question - in the future if an answer to your question will apply to a particular nation's regulations, it's good to request it up front. Otherwise you'll get lots of answers that don't help you.

Welcome to aviation.SE! I made a few small changes to your question, if I got something wrong then feel free to edit again yourself. I assumed that "FL35" means "FL035" and not "FL350" in this case (because you said it was the transition level).

@pondlife. I’m being obtuse here, but personal pet-peeve: Heading is 035, FL is only 35

@Radu094 No problem :-) But maybe it's a regional thing? In the US, flight levels always have three digits. And in South Africa, come to think of it.

Oh, could be a regional....can’t find anything official about it ... maybe an ATC guy can help enlighten us

The direction of the ground track is what matters, not the actual aircraft heading.

The Quadrantal Rule is not binding on aircraft flying VFR, but if the pilot still wants to stick to the rule, he/she should climb to FL045. The rule was "Even plus 500 on magnetic tracks from 270 degrees up to and including 359 degrees." and does not apply at all below FL 030.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
How to find TAS for given CAS, FL and OAT?
Here is another question for my PPL Exam. If anyone can illuminate me with explaining every step to achieve TAS with given parameters, it would be great.
Given:
Calibrated airspeed (CAS): 155 kt. Flight level (FL) 80.
Outside air temperature (OAT): -15° C.
The true airspeed (TAS) equals...
When seeing this question there is only one thing is coming up to my mind and which is: Temperature drops 2° C every 1000 ft but I cannot connect the dots to find TAS.

This answer can help you. All you need to do is convert the FL into a pressure and plug the numbers into the formula given in that answer...

My trusty E6-B flight computer (I can't believe we still teach people to use what is essentially a slide rule) has the following printed on it:

AIRSPEED CORRECTION
Set PRESS. ALT opposite °C in window. Opposite CAS on inner scale read TAS on outer scale. Read Density ALT Centre ▲

Following the instructions and setting -15°C against 8,000 ft reads a TAS of 170 kts for a CAS of 155 kts

There is a huge advantage to a slide-rule over a calculator: slide rule won't have flat battery!

Nor even a dead battery, @JanHudec (for the Americans in the crowd. :D)

@JanHudec that may be an advantage while flying. But in pre-planning not so much.

@Jamiec, having it as a backup in your flight bag in case you need to update your plans in flight is good enough reason to learn basics of its use even if you'll almost never actually use it.

Maybe, you can use this Airspeed Calculator. Using this, you can easily convert between TAS, EAS, CAS. They have also explained the theory behind it.

Your link is broken.

@bogl It's working for me. You can also google search "AeroToolbox Airspeed Conversions", you might get to the webpage.

Phew, looks like my whizz-wheel skills still work. This is why I cant understand why people need to learn how to use it any more. It's not like anyone busts it out while actually flying, and in prep there are a hundred apps/websites which do a better job of explaining it.


text:
What is an appropriate way to practice ATC communications?
I'm a PPL trainee and I'm looking for a way to improve my radio communication.

https://www.liveatc.net/ is a great way to practice but I can't fully understand the conversation between the unit and the aerodrome. If it just had subtitles or general documentation about it, would be great.

Live ATC is an excellent way to listen and get familiar with your local airports procedures. I used to pick out a tail number and then pretended to be that aircraft. When ATC gave instructions, I would say back what I think the response should be.
If there are terms or phrases you don't understand, you should be able to look them up in the Pilot/Controller Glossary.
ATC and pilots should do their best to use the official phraseology in the glossary. However, the goal of communication on the radio should be clarity. If there is something you want to say but don't know how, just say it plainly without worrying about the 'official' wording.

Note that the phraseology differs throughout the world. ICAO phraseology is not quite US phraseology is not quite Canadian phraseology. Make sure you're looking at the correct variant; for example, don't rely blindly on the US FAA's resources if you're training for a European PPL!

Proper phraseology is important, but the over riding intent is clear communication.  Sometimes plain language is the best way to get your point across.  Otherwise you risk sounding like a junior police spokesman trying to use all the right words he was taught in front of news cameras for the first time:  "The perpetrator, um, passed away as a result of, uh... injuries sustained from... the discharge of the responding officer's sidearm..."

If you use MS Flight Simulator on your computer (which you should be) you should look into VATSIM, which is a virtual air traffic control system for people who use Flight Simulator online.  A lot of VATSIM controllers are real controllers, and there are all kinds of resources.

To improve your communications you need to fly. There's a world of difference between practicing on the ground and actually saying it in the air, when you are Aviating and Navigating, There are times you will sound like Porky Pig on speed which is an unavoidable part of being a student and nothing to worry about.
Don't get me wrong, practice is useful, what I found was that the act of saying was not as important as knowing what to say. For that I built a list of the common calls I was likely to be asked to make and thought about the responses.

One thing that one can do, though, especially if they have access to someone else who is used to communicating over simplex radio, is to buy (or borrow) a pair of cheap walkie-talkies, and use those to practice the act of communicating over simplex radio. I had the advantage myself during radiotelephony class of being used to radio; that allowed me to focus on the aviation-specific parts (phraseology, frequencies, standard transponder codes, ...), which was hugely helpful.

What I found helpful was using Anki - a spaced-repetition flashcard learning tool. You can record and add audio to flash cards. So for example, for a flashcard I wrote the context at the top of the flashcard e.g. IFR Flight - requesting taxi clearance. The 'back' (answer) of flashcard would be me impersonating (in an audio clip) what should be said G-HERO, DA62 at Super Flight, with information D, QNH 1009, request taxi.
You could also set it up so the 'front' of the flashcard is a self-recorded audio clip of the ATC, and the back (answer) is an audio clip of what the correct response is.
As my science teacher taught me at school (and which I have never forgotten) - the best way you learn a skill is to test that skill in its correct context. i.e. for radios, test your knowledge via actually hearing and responding audibly to a prompt. Reading radio textbooks or listening to ATC may help, but actually getting the brain working by practicing an audible response will best train you for real flying.

Sounds like non-US phraseology, but why would you report QNH to the controller? Information D (which you’ve just reported) should contain the current QNH and if the actual is different the controller should tell you…

In the UK, in my experience, ATC will tell you the QNH even if you tell them what information X you have copied (unless you tell them what QNH you have copied) E.g. see Pg 99-100 (chapter 4 pg 5).  https://publicapps.caa.co.uk/docs/33/CAP413%20MAY16.2.pdf

Interesting. Thanks.

@Jim UK ATIS quite often reports QNH & QFE, so the point of repeating it in your initial contact is basically telling the controller which you're using.

@Jamiec - So ATC allows pilots to use what they choose and “converts” their altitude instructions to each pilot’s chosen datum?

@Jim No conversion is done. I suspect it's just for controller awareness. ie/ if I read back  QFE Im probably staying in the circuit (pattern). But it's all pretty moot as you've probably had to book out and give details of your sortie anyway!

@Jamiec - Ok thanks. Not having ever operated in a system where that is the case I’m really struggling to see why this complication was ever introduced/condoned/supported.

@Jamiec I'm not too sure. When operating commercially out of British International Airports I have still been expected to state Information and QNH. These same airports never refer to a QFE. I suspect clarification on QNH is primarily due to the complex layout of Class A-E airspace across large areas of the UK, complex STARs/SIDs and high numbers of civil and military traffic densely compacted into a relatively small area - making correct altimetry incredibly important.

a) Get an airband receiver and listen to ATC whenever you have the opportunity.
b) Armchair flying and self-talk ... sounds funny but does work extremely well!


text:
How to calculate the required motor power and rotor size with respect to the weight of quadcopter?
I want to build a quadcopter but don't have any idea about motor and rotor size selection.
Is there a formula or equation to use? What are other things that need to be considered? Trial and error method would be waste of time and money.

The most important thing to remember here is the Purpose. For what purpose do you want to use the Quadcopter?
That being said , let’s start with the very basic .
Required Thrust = ( Weight x 2 ) / 4
In order to choose a motor  you need to determine how much weight you are planning to take, and then work out the thrust required to lift the quadcopter .Also , when purchasing motors  you need to consider Watt’s and Efficiency as well apart from Motor KV and Thrust.The higher the Efficiency, the better it is.The manufacturer/seller of Motors will provide the specifications about the Motor. This will help you to find out the thrust,power, rpm etc of the motor.
http://www.hobbyking.com/hobbyking/store/__28675__D2830_11_1000kv_Brushless_Motor_UK_Warehouse_.html?strSearch=1000kv
Quadcopters have 2 clockwise(CW) and 2 counter-clockwise(CCW) propellers and it has two flight configurations. X config and + config. In X config two arms will face front side while in + config only one arm will face front side. If you are making Quadcopter with plus config you can tune your quadcopter easily by  single axis tuning method .
Single Axis PID Tuning A Quadcopter
Increased propeller pitch and length generally  draws  more current. Also the pitch can be defined as the travel distance of one single prop rotation. In other words, higher pitch means slower rotation, but will increase your vehicle speed which in turn will use more power.If your intention is to do acrobatics, you will need torque propellers which provide more acceleration and it puts less pressure on the power system. Lower pitch propellers will also improve stability.A higher pitch propeller moves greater amount of air, which could create turbulence and cause the aircraft to wobble during hovering. If you notice this with your quadcopter, try to choosing a lower pitched propeller.
http://blog.oscarliang.net/how-to-choose-motor-and-propeller-for-quadcopter/
You may also choose to use this below Quadcopter Calculator. You can dial in everything from motors to props to ESC.
http://www.ecalc.ch/indexcalc.htm

@IRON-MAN: You need excess lift in order to accelerate upwards.

At thrust=weight you can just hover and land, you cannot climb. Weight2 means you can hover at 50% max thrust (since in that case thrust0.5=weight)

The need for thrust greater than weight is not just to be able to climb, but also for attitude control authority.  Three rotors instead of 4 will not provide enough degrees of freedom to maintain attitude control, unless you can also tilt at least one of the rotors or use cyclic.


text:
What is the bar at the top of the tail of the Panavia Tornado IDS for?
What is the bar at the top of the tail of the Panavia Tornado IDS for? (Circled in red)


text:
What is this aircraft?
32°09'16.6"N 110°50'36.4"W, co-ordinates of the aircraft at Davis-Monthan Air Force base.

Source: Google Maps


text:
Why does weather radar not report some precipitation?
Not sure this is the right place for this, but how come I look at the radar sometimes and, despite it clearly raining at my present location, it doesn't show any precipitation? Example is right now at KEWR, it's raining. I can verify that by standing outside. But looking at the radar from several sources (NOAA, weather.com, several iPhone apps) there is nothing on it.
I know about the whole tilt thing but KEWR has a terminal radar quite close as I recall most airports do.

Right now your METAR is saying KEWR 010251Z 03012KT 5SM -DZ BR BKN007 OVC012 14/13 A3025 RMK AO2 SLP243 P0000 60002 T01390133 58001, the -DZ BR means "light drizzle" and mist. It is possible the weather radar doesn't show light drizzle or mist as precipitation.

As for the "why": WX radar detects echo (Doppler shift), so the size of the droplets, their distribution and their relative velocity affect the detection. Small droplets may not be reflective enough. In addition see Doppler dilemma.

Drizzle is a trifecta with WX radar.
First the extremely small particles tend to be stealth, and have much much less reflectivity than larger droplets or snow.
Second, drizzle tends to be low to the ground, and to the radar processor, may look like the ground to anti-clutter algorithms. The low to the ground can also impact how much energy is radiated there, also an anti-ground clutter measure.
Third, drizzle by it's nature tends to be rather stationary.  The air it is in is normally stable, and there is little movement for a Doppler processor to pull out.  The radar processor handles echo data, not just Doppler data, but the Doppler data is used to enhance the sensitivity of the unit.  Generally it works well for moisture which is moving, but drizzle has little motion.  Except downward, which is orthogonal to the radar, and therefore not a factor.
Similarly, most clouds, and smoke may not show up on WX radar. Birds may, as their radar cross section (RCS) is larger, then tend to move, and they tend to move as a mass of points, all which make them more easily trackable with radar.
In summary, the reasons why Doppler WX radar tends to not show drizzle well are: 1. Extremely small particles, 2. drizzle is low to the ground, and 3.drizzle is stationary and therefore not enhanced by Doppler processors.


text:
Are solar / geomagnetic storms real risks for commercial aviation?
Background
Solar storms/flares are solar events sending particles in space that are potentially dangerous on Earth. From Wikipedia:

Solar flares strongly influence the local space weather in the
  vicinity of the Earth. They can produce streams of highly energetic
  particles in the solar wind, known as a solar proton event. These
  particles can impact the Earth's magnetosphere (see main article at
  geomagnetic storm), and present radiation hazards to spacecraft and
  astronauts. Additionally, massive solar flares are sometimes
  accompanied by coronal mass ejections (CMEs) which can trigger
  geomagnetic storms that have been known to disable satellites and
  knock out terrestrial electric power grids for extended periods of
  time.

Source
They are rated by the US NOAA on a scale from 1 to 5. For instance, level 3 events occur about once a year:

S3 (Strong) - Biological: radiation hazard avoidance recommended
  astronauts on EVA. Passengers and crew in commercial jets at high
  latitudes may receive radiation equivalent to approximately 1 chest
  x-ray.

There are also geomagnetic storms listed on the same page.
Question
Is this a real risk for commercial aviation, if so how do airlines treat this risks on affected routes, e.g.:

How are airlines informed?
Are pilot-in-command informed and allowed to veto a flight?
What do they do regarding exposed crews and passengers?

I don't have an answer for you, but I'd imagine you could correlate data between a listing of the last several S3 solar storms and the number of aircraft incidents on those days to see if there's any statistically significant increase in issues. You might have to dig a little deeper and get into maintenance issues, as well - it could cause problems on aircraft that don't make the headlines, yet still are significant enough to warrant repair work after the flight.

The entire Swedish airspace was closed for hours just last year when the radar system failed, allegedly due to a solar storm. No accidents happened, but it was certainly a dangerous situation. So, in terms of acutely taking out critical equipment and thus increasing the risk for mid air collisions, yes, solar storms can be a real risk to commercial aviation.

@J.Hougaard: Be aware this solar activity version is apparently seriously challenged as an attempt to hide a cyber attack by an "APT" ("advanced persistent threat group"...) Thanks anyway for the interesting news, I have no opinion.

Minor, typical solar flares do not pose a significant risk to aviation. Flight planning services, such as LIDO, do not typically include specific information on solar flares or solar activity.
Airlines that require specific information on solar activity for their flight operations would typically refer to these specialised space weather services, such as the Space Weather Prediction Centre (SWPC).
Regulation:
Regulations, such as EU-OPS (EASA), mandate the assessment and management of crew's exposure to cosmic radiation, especially during heightened solar activity. Airlines must monitor solar activity and adjust flight paths or altitudes to minimise radiation exposure. The crew's exposure is tracked to ensure it remains within safe limits. During periods of increased solar activity, advisories may lead to operational changes, such as altering flight routes, particularly over polar regions. The FAA has issued Advisory Circulars that provide information and guidance on measuring and managing crew exposure to cosmic radiation.
While minor solar flares generally do not significantly impact aviation, a major solar event, akin to the Carrington Event of 1859, could have considerable implications:
Impact on Plane’s Avionics:
Aircraft are designed to be resilient against electromagnetic interference, and many modern aircraft are shielded against solar radiation. However, a solar flare of the magnitude of the Carrington Event could significantly disrupt satellite-based systems like GPS, important for navigation. Aircraft are also equipped with Inertial Reference Systems (IRS/INS), but navigational accuracy would deteriorate.
Impact on Radio Communications:
Such a solar event could disrupt the ionosphere, affecting VHF and HF communications. Increased solar radiation and charged particles could lead to elevated radio noise and interference, challenging the clarity and reliability of VHF communications.
Impact on Supporting Infrastructure:
An event similar to the Carrington Event could induce geomagnetic currents, disrupting power grids and causing widespread electrical blackouts. This could significantly impact air traffic control and airport operations, especially in busy airspace and at major airports.
In conclusion, while the aviation industry is not significantly affected by minor solar flares, a major solar event may cause significant disruption with pronounced impacts on safety - aircraft less precise in their navigational position with potentially limited air traffic control communications.

A pilot in command can always veto, scrub, or divert a flight. Per the Federal Aviation Regulations FAR 91.3(a), "The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft." This applies to airline operations (air carriers, FAR Part 121), air taxis and charters (FAR Part 135), and general aviation (FAR Part 91) operations.
A much bigger issue than than the radiation exposure for the people will be the atmospheric effects of the radiation, and how the radiation affects, e.g., satellite navigation. A very strong solar flare can require shutting down some on-orbit satellites to avoid damage—including navigation satellites, such as GPS. A very strong solar flare can ionize the atmosphere to the point it interferes with communications, especially in the HF band used for transoceanic communications.


text:
How much are aircraft nose paintings restricted by regulations?
It's actually surprising to see these old paintings on aircraft noses:

WW2 nose art, source
How much were (and are) these paintings generally restricted or allowed by law, civil regulation and military rules in countries like US, Russia, India, Australia (if the jurisdiction matters for a general answer)?

"countries and societies with relatively low permissiveness for nudity:" - for example?

@Simon: That's not the point, I'm not starting another war... I'm talking about representation in public space.

:) I meant that your question is not clear.  You ask about "low permissiveness" then quote the UK where no-one bats an eyelid.  If you are simply asking about legal or civil restrictions, then perhaps the first sentence should be edited out since it is entirely subjective.

@Simon: I see, edited. I doubt this same picture would be allowed in a truck in the UK or in France, knowing how movie posters are fought...

It used to be that nose art was pretty outlandish and sexually charged, and it remained largely unrestricted as this B-24 from WWII demonstrates.

With the current gender integrated units and women serving in combat squadrons, this kind of stuff is non longer acceptable.  Currently there's a rule, in at least the USAF, that nose art must be 'non-gender specific' i.e. you can't paint naked women on your airplane.

It wasn't allowed back in WWII either, but squadron commanders let them do it because it boosted morale during wartime.


text:
What is the procedure to turn a certified aircraft into an experimental aircraft?
Last year at EAA Airventure I saw a helicopter (can't remember the model, but it was something like a Eurocopter EC135 or similar with a full glass cockpit). It was US registered (N-Number tail) but had "Experimental" written on the door.
When I asked the person at the booth why it was experimental they said it was because they used it as a test platform for new avionics packages, which got me thinking...
Is there a method to transition an aircraft from certified to experimental? Or is this done on a case-by-case basis through the FAA?
I can see advantages for an aircraft owner to want to transition to experimental if they want to keep up on latest (cheapest) non-TSO'd avionics and be able to do more work on the aircraft without an A&P. The downside is obviously higher insurance rates, but I'm not sure it would be a significant difference...

You essentially convert it to Experimental Exhibition, not Experimental Amateur-Built. That means more restrictions, depending on the FSDO. For instance, your operating limitations may prohibit passengers, or require permission for every flight over a given distance.
It is said that the FAA can be sensitive to people trying to put type-certificated aircraft into Experimental category for recreational use. Important advice below is that you should get permission from the FSDO before starting work on the airplane.
Even if you do this (and they likely won't like you converting say a Cherokee or a Cessna 172 to experimental), they will place certain restrictions on use, such as only flying within a 25 mile radius, and every year you may have to submit a "Program Letter" with a list of all the fly-ins and shows you are going to go to (since it is experimental-exhibition category, so you need to exhibit it!)
All that is to say, you probably will have a hard time converting a certificated plane to experimental and using it like it seems you intend to from your question.
Here is the relevant section from FAA Order 8130.2H.

Section 10. Certification and Operation of Aircraft Under the
  Experimental Purpose of Exhibition or Air Racing

General. Under the provisions of § 21.191(d), exhibition aircraft are defined as aircraft that exhibit the aircraft’s flight
  capabilities, performance, or unusual characteristics at air shows,
  fly-ins, and aviation events; for motion picture, television, and
  similar productions; and for the maintenance of exhibition flight
  proficiency, including (for persons exhibiting aircraft) flying to and
  from such events and productions. Under the provisions of § 21.191(e),
  air racing aircraft are defined as aircraft that participate in air
  races, including (for such participants) practicing for such air races
  and flying to and from racing events.

a. Exhibition. A certificate for
  experimental exhibition must only be issued when an aircraft is to be
  used for valid exhibition purposes. Included in those purposes are
  organized air shows, organized fly-in activities, organized
  exhibitions, youth education events, organized aerobatic competition,
  fly-ins or meets, and movie or television productions. The duration of
  an airworthiness certificate for exhibition may be unlimited.

Here is an example of how to do it I found on a old page from the Robinson V8 Seabee Company website. (I found the page in the internet cache, so it is likely this method isn't foolproof)
STEP 1
Submit bill of sale for project Aircraft as "bought for salvage Parts" to the FAA. Add a separate letter of salvage in order to remove it from the FAA registry as Salvaged. This de-registers this A/C and is an important first step.
STEP 2
Obtain written permission from your local FAA Flight Standards District Office (FSDO) inspector in order to remove the data tag from the salvaged project aircraft. This step represents a great opportunity to develop a positive relationship with the FSDO inspector with whom you'll be working to complete the process. Be straightforward and explain that you require his help in order to certify your project in accordance with 14 CFR § 21.193, under a Special Airworthiness Certificate for the purposes of operating an aircraft in the experimental exhibition group 2 - Piston Engine Aircraft category, for the purposes of:

Demonstrating flight proficiency; Demonstrating the superior engine
  reliability of modern V8 engines; and  Participating in exhibition of
  the aircraft at airshows and public event in order to educate the
  public about the unique and interesting characteristics of this
  aircraft

It is important to understand that the FAA FSDO inspectors are busy folks, and that they will appreciate the fact that you've done your homework. Maintain professionalism and don't expect an answer on the spot, as these inspectors have a number of strict procedures and guidelines within which they must work to accomplish the goal of certifying your aircraft. They deal with a great variety of aircraft and requests and may require some time to get up to speed on your specific request and understand the nature of your Robinson V8 aircraft.
STEP 3
Reserve a new N number on the FAA web site.
When your new N-number is confirmed  by the FAA, simply submit forms 8050-88 and 8050-1 for the new N number as:

Manufacturer (preferably your new LLC Company or yourself). It cannot
  be the old manufacturer of the salvaged parts. Model  (Example:
  Military Seabee OA-15) or whatever you want to call it.  It cannot be
  the old model of the salvaged parts.

These forms need to be sent to the FAA Oklahoma City Registration Branch.
When your project is completed and ready for airworthiness inspection and operating limitations, issue a program letter to your FSDO inspector.  With FAA application for airworthiness form 8130.6.  They will take it from there.
Here is an example of program letter:

Program Letter Nxxxx
Date:  May xx, 20xx
To:  Mr. FAA Inspector
Federal Aviation Administration
XXXXX Flight Standards District Office
1234 Maple Lane
anytown, state zipcode
In accordance with 14 CFR § 21.193,  I request a Special Airworthiness
  Certificate for my aircraft Nxxxx for the purpose of operating an
  experimental exhibition, group 2 -  Piston Engine Aircraft. 1) For
  purposes of demonstrating flight proficency.  2) To demonstrate the
  superior engine reliability of modern V8 Engines.  3) To participate
  in exhibition of the aircraft at airshows and public events to educate
  the public about the unique and interesting characteristics of this
  aircraft.
The aircraft description is as follows:
Manufacturer: Your LLC                                    Registration
  No.:    Nxxxx
Model:  Your model
  Serial No.:    xxxxx       Engine Make/Model: Robinson  LSV
  No. of Engines:    01 Propeller Make/Model:    xxxxx
Number of Seats: Four
The aircraft will be available for inspection at it’s base airport:
  (your airport and hangar location).
The aircraft will be weighed prior to flight to determine weight and
  balance data. The marking requirements of Part 45 will be complied
  with prior to flight, including permanent attachment of a fireproof
  identification (data) plate, permanent application of appropriate
  registration marks.
The following placards will be displayed in the cockpit in full view
  of all occupants:
The word “EXPERIMENTAL" displayed near the entrance to the cabin or
  cockpit; minimum 2 inches, maximum 6 inches in height.
"Passenger Warning – This Aircraft Does Not Comply With Federal Safety
  Regulations For Standard Aircraft" .
Instruments and system controls will be adequately marked, identified,
  and function properly prior to flight.
The power plant /propeller will be ground-run to sufficiently
  determine they are operating properly for flight.
The Aircraft will be maintained under an Annual condition inspection
  that meets the scope and detail of 14CFR part 43, Appendix D.
I request that airworthiness certification operating limitations be
  issued permitting me to operate the aircraft in phase one within 50
  Nautical mile radius of (Your Base Airport) with the exception of all
  A,B,C and restricted airspace and avoiding flight over populated
  areas.  Ten hours of  phase one flight tests will  be conducted to
  demonstrate control ability, engine reliability and establish the
  flight envelope.   After Phase 1 flight test completion,  I plan to
  operate the aircraft under Phase two operating limitations under
  VFR/day and VFR/night conditions under a group 2 Experimental
  Exhibition airworthiness certification within the continental U.S.
  proficiency area.
Kind Regards,
You

Jesus, Canuk, be grateful I don't know where your live cause, brother, if I did I'd be giving you a never ending bearhug of gratitude for that incredible answer! Not big on half-assing things, are ya??  I'm the proud owner of a PA38-112 Piper Tomahawk which has the 125 HP upgrade. There literally isn't a more cost effective aircraft, new or used, which more closely matches my specific mission requirements than that little Rocket Sled! The problem is the erroneous ignorance-based stigmas attached to that model for the last 40 years has manifested today into ZERO AP options. I want to do this

Canuk's answer provides a good summary of how a small piston aircraft might get an experimental airworthiness certification. This answer is intended to provide a more general view of what is needed.
FAA Order 8130.2 covers the topic of Airworthiness Certification of Products and Articles. Chapter 4 Section 7 covers general experimental airworthiness certifications.

For an aircraft to be eligible for an experimental certificate, the aircraft must be registered and the applicant must satisfy one or more of the purposes stated in 14 CFR 21.191, as discussed in chapter 4, sections 8 through 11 of this order.

These purposes are:

LSA
Amateur-Built
Exhibition or Air Racing
Research and Development, Showing Compliance With Regulations, Crew Training, Market Surveys, and Operating Kit-Built Aircraft

So if the aircraft will be used for one or more of those purposes, some paperwork and inspections will be required.

The FAA representative should become familiar with the aircraft type and its operational history, if any, before initiating the record and aircraft inspection.
FAA Form 8130-6 is required whenever an airworthiness certificate is issued or amended.

Experimental aircraft will also require a program letter.

The FAA uses the program letter to assist in establishing eligibility for an experimental certificate. The program letter must contain the required items listed in § 21.193 and be detailed enough to permit the FAA to prescribe the conditions and limitations necessary to ensure safe operation of the aircraft. Additional information and guidance concerning program letters can be found in appendix B to this order.

The required items listed include:

Purpose for which the aircraft is to be used
Unless converted from a previously type-certificated aircraft without significant change in the external configuration, the applicant must provide three-view drawings or three-view dimensioned photographs of the aircraft.
Any other pertinent information necessary to safeguard the general public.
For experimental purposes:

Purpose of the experiment to include the aircraft configuration or modifications, and outline the program objectives.
Estimated number of flights or total flight hours, and the period of time (for example, days or months), required for the experiment.
Areas over which the proposed flights are to be conducted.

LSA aircraft assembled from a kit or aircraft manufactured outside the United States have further requirements.
The aircraft must be registered and marked in accordance with part 47 and part 45, respectively.
For a small piston exhibition aircraft, there will also be a records inspection covering items including:

Necessary maintenance, inspection, operating, and flight manuals required to safely operate the aircraft.
Current maintenance records of inspections, overhauls, repairs, time-in-service
Maintenance and modification records for flight control balancing, fabricated parts, and supporting engineering documentation, if required
Appropriately rated FAA-certificated mechanic has made an entry in the aircraft records documenting the applicable inspections
Weight and balance data
Documentation about imported aircraft
Inspection program

Then there will be the aircraft inspection.

Verify instruments, instrument markings, and placards are as required by 14 CFR
Airspeed in knots, altimeters in feet, and distance measuring equipment in nautical miles
Flight control system operates properly
The engine(s), propeller(s), and associated instruments operate in accordance with the manufacturer’s instructions.
The pitot static system and associated instruments operate properly.

If all of this is in order, then the certificate may be issued.

Very detailed, thank you. I'd mark them both answer if it was possible...

Yes there is a method.   And to complicate things, there is more than one kind of Experimental certificates. Different types of certificates have different operating restrictions and bureaucratic overhead (e.g.; Experimental R&D requires annual renewal.) Details are available in the following FAA document:
http://www.faa.gov/documentLibrary/media/Order/8130.2H.pdf

Including the important information from the link would improve this answer.

Even including the document identifier or similar (not just a URL) would improve this answer, because then people can get their hands on the document even if the provided URL itself becomes invalid for some reason. Compare Cool URIs don't change -- in real life, URIs change. A lot.


text:
Could a kilometer of sand as wide as the runway,1 meter deep stop an Airbus A380 if it overshot the runway
An aircraft overshooting the runway could prove to be fatal.  Assuming an Airbus A380 is fully loaded at near take off speed and pilots decide its would be best to abort take off, if they slammed the brakes and they were not as efficient and they approached 1000m of sand as wide as the runway one meter or more deep placed at the end of the runway for safety in likelihood of such incidents, traveling at near take off speed.  Would the sand be able to stop the aircraft?
For the purposes of this question we'll assume the sand is either:
A. Desert sand as fund in the UAE -or-
B. Riversand

Thats what EMAS is for...


text:
What is the backup for a glass cockpit, if a plane loses power to the displays/controls?
I'm assuming there is still power to the rest of the plane - maybe it's an unrealistic scenario.

Duplicate? https://aviation.stackexchange.com/questions/20963/how-are-fly-by-wire-airliners-controlled-in-case-of-complete-electrical-failure

The title says "backup for a glass cockpit" so it's what happens after loss of power to the displays. It's a plausible scenario even in an FBW airliner because there has been at least one A320 incident where a bus failure occurred, the aircraft was dispatched with a deferred fault, and the crew accidentally omitted a reconfiguration step.

I'll answer this question as "If the glass cockpit instrument fail, what are the backup? " This answer will also be General Aviation oriented (as I'm a PPL student)
The short answer is redundancy.
At first, let's look at a G1000 (standard GA glass cockpit) architecture :

The most important components are :

One (or multiple for redundancy) AHRS : gives information about Attitude and Heading of the aircraft, thanks to electronic gyrometres / accelerometres / magnetometres.
One (or multiple) Air Data Computer: gives information regarding airspeed / vertical speed / altitude, thanks to static / dynamic pressure informations.
And two Integrated Avionics Unit, that collect data from AHRS / ADC, and generate the content displayed on screen.

Now, Although the two screens usually don't display the same informations (PFD and MFD), These two systems are standalone : in case of a screen / Avionic unit failure, the second can take other.
Here the goal is to remove all single points of failure.

But what if the whole EFIS fails ?

It is required by law to have backup of essential instruments. The definition of "essential" depends of the type of flight (day VFR, night VFR or IFR?). For some aircraft, there backups are traditional (steam gauge) instruments / others have independent electronic systems, like the new Cirrus SR22 G6 :

all electric !

And in the case of a complete electrical failure?

Depends of the aircraft. In my case, I fly the Robin DR401 (certified for night VFR):

The EFIS is a Garmin G500 (smaller version of G1000) along with a GTN650 GPS.
With such a cockpit, even if I have a complete loss of electrical power, backup instuments would still work :

Altitude, Airspeed and Vertical Speed indicator don't require any power to operate ;
So does the slip/skid indicator (a simple ball)
And the Attitude indicator gyro is powered by a vacuum pump, linked to the engine ; it would thus still operate.

In that case I'd be more concerned about the loss of radio / transponder / flaps control / trim than the loss of instruments!
To summarise, Glass Cockpits are designed to avoid the creation of single point of failure, to reduce the risk of complete loss of instruments, thanks to redundant system / backup instruments / displays... And for all-electric planes, I guess backup power supplies!

Wow - wasn't expect such a complete answer, but thank you.  No more questions on this!

Welcome to Aviation.SE! Great job explaining the redundancies and backups available.

Also, particularly on larger aircraft, redundancy also comes in the form of not just multiple redundant systems, but that the redundant systems themselves are often built on completely different implementation architectures (ie: diversified redundancy).  In this case, something like a systemic component failure or software bug will not affect both of the redundant systems since they should not share a design, manufacturing process, software, etc.  Further reading

Depends on the plane. In my plane, I still have the airspeed indicator, altimeter, vertical speed indicator, turn/slip indicator, compass, and a hand held radio that I can use for comm's, none of which are connected to the electric supply that runs the panel displays. Engine controls are still manual, as is the ailerons/elevator/fins. For night flying, a flashlight or two are kept handy as well.
So fly the plane, figure out where you're going, communicate. (Aviate, navigate,communicate).
Also, I have dual Garmin G5s which are battery backed up, so I might lose the radios, but my main gyro's will still be active for 4 hours in case I lose the other stuff while IFR.

In airliners is a bit different than in General Aviation aircraft, since you have room for a lot more backup systems. Nevertheless, when you lose power on all engines, your glass cockpit screens go black immediately.
But don't worry, you always have an independent instrument called ISFD (Integrated Standby Flight Display for Boeing) or ISIS (Integrated Standby Instrument System for Airbus) which gives you the basic flight parameters in order to keep flying while trying to recover your systems.
Right in that moment, the aircraft will realize of the problem and automatically will release the RAT (Ram Air Turbine) which is a little propeller that drops from the belly of the aircraft providing emergency power for the electric and hydraulic systems.
Eventually, the emergency checklists will guide you to switch on the APU (if you haven't done it yet, like wisely did Capt. Sully). The APU will be running within a few minutes and you will recover all your glass cockpit capability. At that point you will be already troubleshooting your engines or.... looking for a spot to land in the Hudson :)

Not explicitly mentioned in the other answers yet: in almost all cases the electrical power systems feeding the displays and sensors have redundancy in one form or another. Sometimes this is a separate engine-driven alternator or generator, sometimes a backup battery dedicated to a subset of the EFIS hardware that can run it for an hour or so if the main alternator or battery fails (that's the case in the Dynon system in my Lancair).


text:
Climb Performance
You are in an airplane climbing at 750 ft/min. If your ground speed is 90 MPH, by how much will you clear the mountain in front of you that is 10 miles away and 5000 feet above your altitude?

At 90MPH, how many feet/minute are you covering? Multiply that by 750 then subtract 5000. #HomeworkHelp

What did you try?  Where did you encounter difficulty?

Basic rise-over-run algebra, or speed-distance-time. https://www.timecalculator.net/speed-distance-time-calculator

My calculator says you are going to die

Welcome to aviation.SE! You will get a much better response to questions like this if you also tell us what your problem or confusion is with the question. The [tour] be helpful if you're new to StackExchange.

So, 5,000 feet to gain and you're climbing at 750 ft/min. At that rate it would take 5000/750=6.67 minutes (to 2 decimal places) to make it.
A speed of 90 MPH is 1.5 miles per minute. Thus 10 miles at that speed would be 10/1.5=6.67 minutes. Hmm, same value. I would suggest turning slightly to avoid the peak.
Seriously, the difficulty is that you can't depend on the kind of precision seemly presented by the the simplicity of the problem as stated. Here are a few things that I can think of offhand that need to be taken into account:

First, just to clear up a units consideration that bothers the likes of me with an nitpicking mind, whomever wrote the question would be better of stating the distance in either nautical miles or kilometers rather than statute miles and their respective speeds. Aviation no longer uses statute miles to speak of.
Depending on the aircraft, you might not be able to maintain the starting rate of climb as you gain altitude. Normally aspirated engines typically lose available power with a gain of altitude.
In the real world, there is always wind overall, and it changes with altitude. If that wind overall was a headwind, that would help you clear the mountain. HOWEVER, climbing toward a mountain on it's leeward side, especially if it is part of a ridge system, invites having to contend with serious downdrafts (and if there's a lenticular cloud over the peak, don't even think of it).
It's unrealistic to depend on your groundspeed to remain constant.

So, while the theoretical answer to the question is that you will have 0 (that's zero) clearance, unless my 80 year-old brain is again malfunctioning, the practical answer is that you should clear all high terrain by, say, a thousand feet or more, and always leave yourself a way to turn toward lower terrain.

Great practical context to a theoretical exercise, thank you!

1. At 90 MPH How long will it take to go 10 miles?
$ \frac{60\:minutes}{90\:miles} \cdot 10\:miles \ = 6\colon40\: minutes$

2. How much altitude will you gain in 6:40, at 750fpm?
$6 \frac{2}{3}minutes \cdot \frac{750 feet}{minute} = 5,000\:feet$

3. If you gained 5,000 feet, by how much will you clear the mountain in front of you?
You're not going to make it.

Agree with the conclusion (even Bald Mountain). However 2 things were left out. 1. Loss of performance with climb.  Increase in true airspeed with climb. Factoring both in, I'd go for a climbing turn to a different course.


text:
Why do airplanes use an axial flow jet engine instead of a more compact centrifugal jet engine?
Axial flow jet engines take up a lot of space. Centrifugal jet engines create high pressure. Can you create a centrifugal air pump that pushes as much air as a axial jet engine. Centrifugal air engines reach higher speeds from my research. What are the main disadvantages of centrifugal air engines from the standard axial engines.

Centrifugal compressors only produce a more compact engine at low mass flow, which means low thrust.
The amount of thrust an engine can produce is proportional to its intake area times exhaust velocity. Increasing the latter is undesirable, as energy and thus fuel consumption is proportional to velocity squared. So engine designers target mass flow to gain more thrust, not more velocity.
Since they are 3D structures, in a basic solid design (that you'd find in early jets and small modern turbines), the volume of a centrifugal compressor grows in cubic proportion to its diameter, while frontal area, which limits its mass flow and thus its thrust, increases only as diameter squared. This creates a cube-square law.
Large real-life parts are filled with lightening and cooling channels, so the mass-to-area law is more complex. Still, it cannot eliminate the volume effect entirely. The end result is that the mass of centrifugal compressors grows considerably faster than their mass flow.
At the highest power levels, centrifugal compressors become prohibitively heavy even for fixed powerplant machinery, where durability otherwise trumps weight, so the largest base load powerplants run all-axial. With axial compressors, the flat design with a short air flow path allows mass to only grow in direct proportion to mass flow, and very powerful engines can be built within reasonable dimensions.
It's not pure cube-square law in either case, but it's something like k1*massflow^[2.5, 2.8] for centrifugal versus k2*massflow^[2.2, 2.4] for axial, where k2>k1, giving centrifugal compressors some advantage in small sizes. Centrifugals are also much cheaper to produce (at least small ones).
High-performance engines, such as those in commercial aircraft, also need to pack more thrust into the smallest cross-section they can, while maintaining efficiency, so as to reduce drag and also fit under the wings, enabling heavier jets. Axial compressors offer a lot more intake area for any given cross-section - thus more thrust.
The smallest jets, where thrust requirements are small and the engine's cross-section is very small compared to the fuselage, can afford the extra diameter of a centrifugal or diagonal flow compressor. Yes, it's the same cube-square law (also reduced somewhat in practice) that keeps the engine cross-section to total cross-section ratio increasing as aircraft go up in size. Small centrifugal compressors are simpler, easier to build, and more robust than small axial ones.
So in every industry, as power grows, there is a crossover point from centrifugal to axial. For aircraft where drag is critical, it's just above small bizjets, mobile ground and helicopter turbines stay centrifugal or mixed up to a few MW, and in the tens of megawatts even fixed powerplants switch from axial/centrifugal to all-axial.
Engines close to that crossover point typically combine axial and centrifugal stages. Newer diagonal compressors are in-between and quite good, offering an even more tailored compromise.

Thank you, a very thorough yet easy to follow answer.

"Centrifugal compressors are only more compact at low mass flow" no they aren't, they are more compact at any mass flow. A large part of the frontal area cannot be used for airflow, is the issue in larger engines.

@Koyovis Define "compact" then. Inlets have to be sized for required airflow, so, for airliner engines that are only as wide as their inlets, a wider compressor will mean a wider and heavier engine. Centrifugal compressors are compact in smaller engines, but supersizing them doesn't maintain that - axials are better at ingesting as much air as possible in given engine size.

"The necessary mass of a centrifugal compressor grows in cubic proportion to its diameter" Not necessarily: The length of an engine might even shrink when increasing the diameter. In this case the volume (and therefore the weight) would grow less than squared.

Mass of the centrifugal compressor grows exponentially compared to the mass of three axial stages? The centrifugal compressor can be hollowed out, the main stress bearing material is at the impeller tip.

@Koyovis The mass question is really quite complex. You can hollow out more material from a larger impeller, but there's more centripetal force from the heavy tips. Overall the end result is that the largest centrifugal compressors are much heavier than their axial counterparts, while for small compressors all three solutions are mass-competitive.

“The mass question is really quite complex.” Exactly my point, yet you present it as a square-cube law.

@Koyovis Well, saying "it's complex" largely equates to "it's magic", so I went for a simplification. That simplification still holds true in a naive case, and for real-life scenarios, it correlates with them. I'll edit to clarify that.

Axial turbine engines take up a lot of space...lengthwise. Centrifugal compressors are shorter and wider, and are very often used in turboprop and turboshaft engines, for instance the Rolls Royce Dart is a single axis turboprop engine. The photo demonstrates the compactness of the engine...lengthwise.
.

Can you create a centrifugal air pump that pushes as much air as a axial jet engine.

Yes you can. It will have two main issues:

The losses in the centrifugal compressors will be higher than for an axial configuration reaching the same compression ratio.
Part of the frontal area cannot be used for airflow.

What are the main disadvantages of centrifugal air engines from the standard axial engines.

Centrifugal compressors:

Are slightly less efficient than axial compressors (for a given compression ratio).
Expel the airflow perpendicular to free stream, so that if multiple stages are required the airflow must be guided into quite a bendy pathway, with additional negative impact on efficiency.
Result in an engine with a larger frontal area.

Advantages are:

Centrifugal compressors achieve higher compression ratios than axial compressors - per stage. Compression ratios of 4 - 6, while an axial stage can only do 1.4 - 1.6.
They are of a more robust and often less costly construction.

Larger engines (high mass flow, high compression ratio and minimal frontal area) use axial compressors almost exclusively: the internal losses are lowest. Centrifugal compressors are used for design cases where other factors than efficiency are of interest, such as cost and limitation of length for helicopter turboshafts.
An example of the use of a centrifugal compressor in a turbofan engine is the Garrett AiResearch ATF3. A 3-shaft engine, with the fan on shaft 1, five axial stages on shaft 2, and a centrifugal stage on shaft 3.

Picture source
The hot exhaust stream is deflected back into the fan bypass, which cools it down and results in a low IR signature. This engine is used in the Dassault Falcon. Note that there is no principal technical difficulty to scale this engine up to A380 level, other than the decreased efficiency due to the multiple deflections in the airstream. The wider frontal area is not a problem in the compressor part, and the total compression ratio increases a lot using this final stage.
As in the ATF3, centrifugal compressors are often combined with an axial stage, which pre-whirls the air stream into the centrifugal compressor and increases both efficiency and max compression ratio per single stage, as compared to a flat single stage.

While a centrifugal compressor can acheive greater compression than a single compressor stage in an axial flow engine, the axial flow design allows for multiple compressor stages, achieving higher overall compression of the air and consequently greater efficiency. Centrifugal flow jet engines are, however, tough and reliable.

Centrifugal compressors can also be multi-staged.

Centrifugal compressors are limited by the size and sharp angle of the diffuser duct that has to straighten out the outward flowing air flow from the impeller compressor and reroute it back to the combustion chambers. This restricts the amount of air that can flow through this engine. Axial flow engines are straight through design and don't have this limitation.

You may expand your answer so that it is clear you add something to existing answers

All existing centrifugal-compressor aircraft engines have been turbojets or turboprops.
Aside from their low power compared with modern turbofans (the Rolls-Royce Dart mentioned in another answer produced about 1 MW, compared with 50MW for a modern large turbofan engine core) the larger diameter of a centrifugal compressor would make it hard to design an efficient turbofan, by restricting the area of the fan duct.
Increasing the outer diameter of the fan blades to enlarge the bypass duct is not a practical option, since it is limited by the ground clearance of the aircraft. Trying to avoid that issue with very large diameter tail-mounted engines would just create a different set of design problems.

Not all; the Pratt & Whitney Canada PW600 is a turbofan (albeit a tiny one) with a centrifugal core compressor.

The RR Dart powers a propeller. Talk about a large diameter fan...


text:
Could a Dyson fan displace more air without increasing the fan size?
So the Dyson Fan is cool. But it has a thrust to weight ration of 0.6. Not very efficient for flight. Its great at sucking large amounts of air but not at a very high velocity. Thrust is small amounts of air at high speed correct me if I'm wrong. Is there any way to get the Dyson Fan to blow air at a faster speed without increasing the size of the fan.

I saw that but I asked if there was a way to accelerate the air faster using this air foil

What can’t a blow harder do?

no im trying to see if you can take the force of a jet engine and apply it to this Dyson Fan design. is it possible

Thrust is small amounts of air at high speed correct me if I'm wrong.

No, more air at lower speed is more efficient. Thrust is derivative of momentum added to the air, while power is derivative of kinetic energy added to it. Since momentum grows with velocity, but energy with square of velocity, accelerating more air by less creates the same thrust with less power.
Dyson fan works by blowing a thin stream of high velocity air along the ring, which then pulls in more air to create a very smooth air flow through the ring. To create this high velocity flow, you have to provide a lot of energy, which will then dissipate as heat when the streams mix, but you have no way to recover any of it as it happens already behind the fan. So it is very inefficient and while adding power will make it generate more thrust, it will only further reduce the efficiency as the flow speed increases.

Yes you can make a Dyson fan blow more air without making it larger - just increase the speed and torque. It will get louder and consume (probably disproportionately) more power.
No this would not be remotely practical as a means of aircraft propulsion. Existing turbofans and propeller designs are highly optimized and pretty much the best tools for the job.


text:
What is the problem in the satellite data of MH370
In the Inmarsat data of MH370, there are handshakes (BTO) with time (UTC) at: 19:41, 20:41, 21:41, 22:41, 00:11,00:19. Normally it pinged every hour, but why the 2nd to last happened at 00.11 that was 1.5 hour after the previous one? The last one happened at 00:19 is for what reason?
Also can ping be stopped manually, e.g. by turning off the power, then there will be no ping?

This was explained back in 2014 when the data was released. It is consistent with a loss of power due to fuel exhaustion, followed by battery power restoring communication.

And the lack of signal after 00:19 indicates that the batteries were also dead by that time.


text:
Can a P51 outrun an missile?
No explanation needed, can a P-51 Mustang outrun a missile?

Voting to close as too broad - it depends on the missile. A Vietnam-era missile is very different from a modern one, for example.

Cruise missiles counts? and a V-1?

How fast is the missile travelling?  Missiles don't all travel at the same speed.  (Though I agree with Ron ....)

Sorry, but how come the question attracts down votes while there are two upvoted answers? It can't be that bad then, can it.

@Koyovis I didnt specified an missile thats why

Which Missile? Any Air-to-Air missile manufactured since they were first invented travels much faster than a P-51, so NO. Very early air-to-ground missiles are subsonic, (German V-1), so maybe, but modern cruise missiles , USAF ALCM, Navy tomahawk can get to 550 Mph, so NO)

Explanation very much needed

The P-51 Mustang is not designed to go supersonic, in fact no propeller airplane is designed to do that...
Can propeller driven aircraft sustain speeds at or above Mach 1?
For example, the Republic XF-84H is the fastest propeller plane ever built, is also the loudest. The propeller tips going supersonic mean that the airplane is incredibly loud, so loud that it causes injuries.
Anyway, the Thunderscreech can hit top speeds of about Mach 0.9. A stock P-51 Mustang can hit about 440mph. Missles, like the AIM-9 Sidewinder can travel at speeds exceeding Mach 2.5. Mach 1 at sea level is around 760mph. Mach 2.5 is 1,918mph. The AIM-9's range is 22 miles, so it can travel 32 miles per minute or about half a mile per second. At the Mustangs top speed of 440mph, the only way the Mustang could "out run" the missile is if the Mustang was about 15 miles ahead traveling at top speed. Even the Thunderscreech would have a tough time outrunning one at full speed without a significant head start.
So the short answer is no, the Mustang is not capable of outrunning an air-to-air missile. Even surface-to-air missiles have a speed between Mach 1.75 and Mach 2 with similar ranges.
Early missles, like the K-13 built in 1960 had a top speed of Mach 2.5, so it wouldn't matter if it happened 50 years ago or today.

Now I wonder wether the guidance system on the missile will even track the P-51. Its infrared signature is very different from that of modern jets and only if the missile uses radar I see a chance that it will "see" the P-51 as a target.

Agree.  I have always wondered if a sufficiently rich or lean piston engine would attract an IR seeker.

@PeterKämpf I'm not sure it's all that different, the EGT of the 2400+hp Merlin engines (400-700°C) isn't all that different than the exhaust turbine temperatures of jet aircraft. Combined with the 12 cylinder direct exhaust the cowling area is probably pretty hot compared to the rest of the airframe (and surrounding sky). Here is the Sidewinder hitting an F6F Hellcat (Piston) Drone

@RonBeyer: Looks convincing. Thank you for the prompt answer.

In counterpoint to @Ron Bayer's answer:
During the V-1 attacks in 1944 and 1945, modified P-51s (among other aircraft) were used to intercept and destroy the "cruise missiles" before they reached their intended targets.
Both gunfire and "tipping"(putting your wing 6 inches under the V-1 wing and using the airflow to tip the V-1 over) were used.  P-51 Mustangs destroyed 232 V-1s.
See https://en.wikipedia.org/wiki/V-1_flying_bomb
Technically, the P-51s weren't "outrunning";  they were catching...

They could do that only because they were using "pytogras" technique ! Instead of tailing and trying to catch from behind, they take off and fly half vertically and half horizontally to catch up... P51s werent fast enough to overspeed the V2's

I would just like to add that considering most early missiles were heat-seeking and infrared guided, the P-51's heat signature thanks to its relatively cool running inline wouldn't be a sure detection by the seeker head. However, the all metal, HIGHLY conventional design would be an easy pick for radar-seeking seekers. If that adds anything to your question.